1. Field of the Invention
The present invention relates to a digital image input/output apparatus or a digital copying machine with an image compressing/expanding means and an image storage means.
2. Description of the Related Art
In conventional digital copying machines, input original image information from a scanner is temporarily held in a page buffer. Whenever an original is input from the scanner, the image information is compressed, and the compressed image information of a plurality of originals is stored in a file buffer.
These conventional digital copying machines have a so-called electronic sort function by which the compressed image information stored in the file buffer is subjected to single-side or double-side printing in a sort mode or a group mode by appropriately changing the output order of the image information.
When a large quantity of originals are to be copied, for example, the file buffer sometimes becomes full while the originals are being input from the scanner. If this is the case, a series of original input operations are interrupted, and the copied products of originals that are input up to this point are output, thereby completing a single job.
If the number of originals is large, therefore, it is necessary to output the copied products before the remaining originals can be input, resulting in a cumbersome operation.
Also, a plurality of originals are joined and output in the form of a single copy in some instances such as in double-side printing. If the file buffer is filled up after an original for one side is input, the other side of a copy to be subjected to double-side printing remains blank. The result is that the copying operation cannot be well completed.
It is an object of the present invention to provide a composite image forming apparatus capable of accurately performing a copying operation in a copying machine which compresses and stores a plurality of originals, even if a memory for storing the compressed information becomes full.
The present invention is an image forming apparatus comprising means for reading image information of an original, means for storing the image information of a plurality of originals read by the reading means, means for performing image formation such that the image information of at least two of the originals stored in the storing means is formed on a single image formation medium, means for detecting that the storing means becomes full, and means for, when the detecting means detects that the storing means becomes full while the reading means is performing a series of read operations, controlling the image forming means to form images of the image information of the originals which are stored in the storing means and images of which are to be formed on a single image formation medium, erasing the image information whose images are thus formed, and controlling the storing means to store the image information read by the reading means.
According to the present invention with the above arrangement, when the storing means, such as a file buffer, becomes full while the image information of a plurality of input originals is being compressed and stored in the storing means, the image information already stored is printed on a sheet as an image formation medium, and the printed image information is erased from the storing means. Consequently, an empty area is formed in the storing means, so the image information of the rest of originals can be read and stored.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.